Circuits and methods related to switchless carrier aggregation in radio-frequency receivers

ABSTRACT

Circuits and methods related to switchless carrier aggregation in radio-frequency receivers. In some embodiments, a carrier aggregation (CA) circuit can include a first filter configured to allow operation in a first frequency band, and a second filter configured to allow operation in a second frequency band. The CA circuit can further include a first signal path implemented between the first filter and an output node, with the first signal path including a plurality of amplification stages configured to amplify a first radio-frequency (RF) signal. The first signal path can be substantially free of switches. The CA circuit can further include a second signal path implemented between the second filter and the output node, with the second signal path including a plurality of amplification stages configured to amplify a second RF signal. The second signal path can be substantially free of switches.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to U.S. Provisional Application No.61/978,810 filed Apr. 11, 2014, entitled CIRCUITS AND METHODS RELATED TOSWITCHLESS CARRIER AGGREGATION IN RADIO-FREQUENCY RECEIVERS, thedisclosure of which is hereby expressly incorporated by reference hereinin its entirety.

BACKGROUND

1. Field

The present disclosure relates to carrier aggregation in radio-frequency(RF) receivers.

2. Description of the Related Art

In some RF applications, cellular carrier aggregation (CA) can involvetwo or more RF signals being processed through a common path. Forexample, carrier aggregation can involve use of a path for a pluralityof bands having frequency ranges that are sufficiently separated. Insuch a configuration, simultaneous operation of more than one band canbe achieved.

SUMMARY

In a number of implementations, the present disclosure relates to acarrier aggregation (CA) circuit that includes a first filter configuredto allow operation in a first frequency band, and a second filterconfigured to allow operation in a second frequency band. The CA circuitfurther includes a first signal path implemented between the firstfilter and an output node. The first signal path includes a plurality ofamplification stages configured to amplify a first radio-frequency (RF)signal. The first signal path is substantially free of switches. The CAcircuit further includes a second signal path implemented between thesecond filter and the output node. The second signal path includes aplurality of amplification stages configured to amplify a second RFsignal. The second signal path is substantially free of switches.

In some embodiments, the first signal path and the second signal pathcan be parts of a low-noise amplifier (LNA). The first signal path andthe second signal path being substantially free of switches can allowthe CA circuit to operate with a reduced noise figure.

In some embodiments, the plurality of amplification stages of each ofthe first signal path and the second signal path can include a firststage and a second stage. The first stage can be configured to convertthe respective RF signal into current. The second stage can beconfigured to add the current.

In some embodiments, the first stage of each of the first signal pathand the second signal path can include a first bipolar junctiontransistor (BJT) configured to receive the respective RF signal throughits base and yield an output through its collector. The CA circuit canfurther include a bias circuit coupled to the first BJT. The biascircuit can include a switchable bias supply path between a bias nodeand the base, with the switchable bias supply path configured to becapable of being turned on or off to activate or deactivate therespective first BJT. The bias circuit can further include a switchableshunt path configured to provide a shunt path when the respective firstBJT is deactivated.

In some embodiments, the first BJT of each of the first signal path andthe second signal path can include an emitter coupled to ground throughan inductance. The emitters of the first BJT of the first signal pathand the second signal path can be coupled to ground through separateinductances, or through a common inductance.

In some embodiments, the second stages of the first signal path and thesecond signal path can be provided by a shared second BJT configured toreceive the RF signals from the first BJTs through its emitter and yieldan output through its collector. The shared second BJT can be configuredto receive a cascode bias voltage Vcas through its base. The cascodebias voltage Vcas can be adjustable depending on the number of inputsinto the shared second BJT.

In some embodiments, the second stage of each of the first signal pathand the second signal path can include a separate second BJT configuredto receive the RF signal from the respective first BJT through itsemitter and yield an output through its collector. Each separate secondBJT can be configured to receive its respective cascode bias voltageVcas through its base.

In some embodiments, the first filter and the second filter can be partsof a diplexer. The diplexer can include an input port configured toreceive an RF signal from an antenna.

In some embodiments, each of the first signal path and the second signalpath can be capable of being in an active state or an inactive state toallow the CA circuit to operate in a CA mode or a non-CA mode withoutseparate switches along the first signal path and the second signalpath. The active state or the inactive state for each of the firstsignal path and the second signal path can be achieved by activating ordeactivating the respective first stage.

According to some implementations, the present disclosure relates to aradio-frequency (RF) module that includes a packaging substrateconfigured to receive a plurality of components, and a carrieraggregation (CA) circuit implemented on the packaging substrate. The CAcircuit includes a first filter configured to allow operation in a firstfrequency band and a second filter configured to allow operation in asecond frequency band. The CA circuit further includes a first signalpath implemented between the first filter and an output node, with thefirst signal path including a plurality of amplification stagesconfigured to amplify a first radio-frequency (RF) signal, and the firstsignal path being substantially free of switches. The CA circuit furtherincludes a second signal path implemented between the second filter andthe output node, with the second signal path including a plurality ofamplification stages configured to amplify a second RF signal, and thesecond signal path being substantially free of switches.

In some embodiments, each of the first filter and the second filter caninclude a surface acoustic wave (SAW) filter. The first SAW filter andthe second SAW filter can be implemented as a diplexer. The plurality ofamplification stages for each of the first signal path and the secondsignal path can be part of a low-noise amplifier (LNA).

In some embodiments, the RF module can be a front-end module. In someembodiments, the RF module can be a diversity receive (DRx) module.

In some teachings, the present disclosure relates to a method forfabricating a radio-frequency (RF) module. The method includes providingor forming a packaging substrate configured to receive a plurality ofcomponents, and implementing a carrier aggregation (CA) circuit on thepackaging substrate. The CA circuit includes a first filter configuredto allow operation in a first frequency band and a second filterconfigured to allow operation in a second frequency band. The CA circuitfurther includes a first signal path implemented between the firstfilter and an output node, with the first signal path including aplurality of amplification stages configured to amplify a firstradio-frequency (RF) signal, and the first signal path beingsubstantially free of switches. The CA circuit further includes a secondsignal path implemented between the second filter and the output node,with the second signal path including a plurality of amplificationstages configured to amplify a second RF signal, and the second signalpath being substantially free of switches.

In accordance with a number of implementations, the present disclosurerelates to a radio-frequency (RF) device that includes a receiverconfigured to process RF signals, and an RF module in communication withthe receiver. The RF module includes a carrier aggregation (CA) circuithaving a first filter configured to allow operation in a first frequencyband and a second filter configured to allow operation in a secondfrequency band. The CA circuit further includes a first signal pathimplemented between the first filter and an output node, with the firstsignal path including a plurality of amplification stages configured toamplify a first radio-frequency (RF) signal, and the first signal pathbeing substantially free of switches. The CA circuit further includes asecond signal path implemented between the second filter and the outputnode, with the second signal path including a plurality of amplificationstages configured to amplify a second RF signal, and the second signalpath being substantially free of switches. The RF device furtherincludes an antenna in communication with the RF module, with theantenna being configured to receive the RF signals.

In some embodiments, the RF device can be a wireless device. Such awireless device can be, for example, a cellular phone. In someembodiments, the antenna can include a diversity antenna, and the RFmodule can include a diversity receive (DRx) module). In someembodiments, the wireless device can further include an antenna switchmodule (ASM) configured to route the RF signals from the diversityantenna to the receiver. The DRx module can be implemented between thediversity antenna and the ASM.

For purposes of summarizing the disclosure, certain aspects, advantagesand novel features of the inventions have been described herein. It isto be understood that not necessarily all such advantages may beachieved in accordance with any particular embodiment of the invention.Thus, the invention may be embodied or carried out in a manner thatachieves or optimizes one advantage or group of advantages as taughtherein without necessarily achieving other advantages as may be taughtor suggested herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a carrier aggregation (CA) configuration that includes alow-noise amplifier (LNA) circuit configured to receive two inputs andyield an output.

FIG. 2 shows that one or more features of the present disclosure canalso be implemented in aggregation of more than two frequency bands.

FIG. 3 shows an example where an LNA circuit having one or more featuresas described herein can be implemented to provide CA functionalitieswithout switches along the signal paths.

FIG. 4 shows an example of a multiband receiver architecture configuredto operate in three frequency bands utilizing a common antenna and acommon LNA.

FIG. 5 shows another example of a multiband receiver architectureconfigured to operate in three frequency bands utilizing a commonantenna and three separate LNAs.

FIG. 6 shows a carrier aggregation (CA) architecture that includes anLNA circuit configured such that switches between band-pass filters andLNA(s) can be eliminated, and yet allow the CA architecture to operatein a CA mode or a non-CA mode.

FIG. 7 shows an LNA circuit that can be implemented as a more specificexample of the LNA circuit of FIG. 6.

FIG. 8 shows an LNA circuit that can be implemented as another morespecific example of the LNA circuit of FIG. 6.

FIG. 9 shows an LNA circuit that can be implemented as yet another morespecific example of the LNA circuit of FIG. 6.

FIG. 10 shows a process that can be implemented to fabricate a devicehaving one or more features as described herein.

FIG. 11 shows that in some embodiments, one or more features asdescribed herein can be implemented a module configured for RFapplications.

FIG. 12 shows an example wireless device having one or more advantageousfeatures described herein.

FIG. 13 shows another example wireless device having one or moreadvantageous features described herein.

FIG. 14 shows that one or more features of the present disclosure can beimplemented in a diversity receive module.

FIG. 15 shows an example wireless device having the diversity receivemodule of FIG. 14.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

The headings provided herein, if any, are for convenience only and donot necessarily affect the scope or meaning of the claimed invention.

Cellular carrier aggregation (CA) can allow two or more radio-frequency(RF) signals to be processed through a common path. For example, carrieraggregation can involve use of a path for a plurality of bands havingfrequency ranges that are sufficiently separated. In such aconfiguration, simultaneous operation of more than one band is possible.

In the context of a receiver, carrier aggregation can allow concurrentprocessing of RF signals in a plurality of bands to provide, forexample, high data rate capability. In such a carrier aggregationsystem, it is desirable to maintain a low noise figure (NF) for each RFsignal. When two bands being aggregated are close in frequency,maintaining sufficient separation of the two bands is also desirable.

FIG. 1 shows a carrier aggregation (CA) configuration 100 that includesa low-noise amplifier (LNA) circuit 110 configured to receive two inputsand yield an output. The two inputs can include a first RF signal and asecond RF signal. The first RF signal can be provided to the LNA circuit110 from a common input node 102 (RF_IN), through a first path 104 athat includes a first filter 106 a. Similarly, the second RF signal canbe provided to the LNA circuit 110 from the common input node 102(RF_IN), through a second path 104 b that includes a second filter 106b. As described herein, the LNA circuit 110 can be configured such thatthe output at a common output node 114 is an amplified RF signal thatincludes two separated frequency bands associated with the first andsecond RF signals. As also described herein, the LNA circuit 110 can beconfigured to yield desirable performance features such as low loss, lownoise figure, and high isolation between the two signal paths 104 a, 104b.

Various examples herein, including the example of FIG. 1, are describedin the context of aggregating two frequency bands. However, it will beunderstood that one or more features of the present disclosure can beimplemented in aggregation of more than two frequency bands. Forexample, FIG. 2 shows a CA configuration 100 where three RF signals areseparated at a common input node 102 (RF_IN), processed through theirrespective filters 106 a, 106 b, 106 c, and processed by an LNA circuit110 to yield an amplified RF signal at a common output node 114(RF_OUT). It will be understood that other numbers of frequency bandscan also be aggregated utilizing one or more features as describedherein.

The aggregation configurations 100 of FIGS. 1 and 2 can be implementedin a number of RF applications. FIG. 3 shows a more specific examplewhere an LNA circuit 110 having one or more features as described hereincan be implemented to provide CA functionalities without switches, orwith reduced number of switches, along the signal paths. The LNA circuit110 can be configured to receive, for example, two inputs and yield anoutput. The two inputs can include a first RF signal and a second RFsignal. The first RF signal can be provided to the LNA circuit 110 froma common input node 102 (RF_IN), through a first path that includes afirst band-pass filter 122. Similarly, the second RF signal can beprovided to the LNA circuit 110 from the common input node 102 (RF_IN),through a second path that includes a second band-pass filter 124. Asdescribed herein, the LNA circuit 110 can be configured such that theoutput at a common output node 114 is an amplified RF signal thatincludes two separated frequency bands associated with the first andsecond RF signals. As also described herein, the LNA circuit 110 can beconfigured to yield desirable performance features such as low loss, lownoise figure, and high isolation between the two input signal paths.

In some embodiments, the LNA circuit 110 can be configured to operatewith a sufficiently wide bandwidth to effectively amplify the first andsecond bands. In some embodiments, the pass-band filters 122, 124 can beimplemented in a number of ways, including, for example, as surfaceacoustic wave (SAW) filters. Although various examples are describedherein in the context of SAW filters, it will be understood that othertypes of filters can also be utilized.

As described herein, the aggregation configuration 100 of FIG. 3 canprovide a number of advantageous features over other receiverconfigurations. For example, FIG. 4 shows a multiband receiverarchitecture 10 configured to operate in three frequency bands utilizinga common antenna (not shown) and a common LNA 18. An RF signal from thecommon antenna is shown to be received as an input signal RF_IN; andsuch an input signal can be routed through one of the three paths by afirst switch 12 and a second switch 16. For example, the first andsecond switches 12, 16 in the states as shown allow the input signal tobe routed to a first band-pass filter 14 a to yield a first filteredsignal corresponding to the first frequency band. If operation in thesecond frequency band is desired, the first and second switches 12, 16can be set so as to route the input signal to a second band-pass filter14 b to yield a second filtered signal corresponding to the secondfrequency band. Similarly, if operation in the third frequency band isdesired, the first and second switches 12, 16 can be set so as to routethe input signal to a third band-pass filter 14 c to yield a thirdfiltered signal corresponding to the third frequency band.

In the example of FIG. 4, operation in CA mode is generally notpossible, since turning on two paths at the same time results in the twofilter outputs to be shorted. Further, the switches in the architecture10 can yield performance and/or design challenges. For example, thesecond switch 16 can result in degradation of, for example, noise figureperformance. In another example, the switches and the LNA may need to beof different processes (e.g., silicon-on-insulator (SOI) for theswitches and bipolar junction transistor (BJT) for the LNA) for desiredperformance; and use of such different processes can result insignificant increases in device size and/or cost.

FIG. 5 shows another example of a multiband receiver architecture 20configured to operate in three frequency bands utilizing a commonantenna (not shown) and three separate LNAs 26 a, 26 b, 26 c. An RFsignal from the common antenna is shown to be received as an inputsignal RF_IN; and such an input signal can be routed through one of thethree paths by a first switch 22 and a second switch 28. For example,the first and second switches 22, 28 in the states as shown allow theinput signal to be routed to a first band-pass filter 24 a to yield afirst filtered signal corresponding to the first frequency band; andsuch a filtered signal is shown to be provided to the first LNA 26 a. Ifoperation in the second frequency band is desired, the first and secondswitches 22, 28 can be set so as to route the input signal to a secondband-pass filter 24 b to yield a second filtered signal corresponding tothe second frequency band; and such a filtered signal is shown to beprovided to the second LNA 26 b. Similarly, if operation in the thirdfrequency band is desired, the first and second switches 22, 28 can beset so as to route the input signal to a third band-pass filter 24 c toyield a third filtered signal corresponding to the third frequency band;and such a filtered signal is shown to be provided to the third LNA 26c.

In the example of FIG. 5, the second switch 28 being implemented afterthe LNAs can solve, to a large degree, the noise figure degradationproblem associated with the example of FIG. 4, since the noiseassociated with the second switch is not amplified. However, thearchitecture 20 of FIG. 5 typically requires a separate LNA for eachfilter of the multiple signal paths. Such multiple LNAs typically resultin increased size, cost, and/or complexity associated with the receiverarchitecture. Further, operation in CA mode is typically not possiblesince enabling two paths at the same time results in LNA outputs to beshorted.

FIG. 6 shows a carrier aggregation (CA) architecture 100 that includesan LNA circuit 110 configured such that switches between band-passfilters and LNA(s) can be eliminated, and yet allow the CA architecture100 to operate in a CA mode or a non-CA mode. The LNA circuit 110 can beconfigured to receive a plurality of inputs (e.g., two inputs) and yieldan output. The two inputs can include a first RF signal and a second RFsignal separated at a common node 130. The first RF signal can beprovided to the LNA circuit 110 from a common input node 102 (RF_IN),through a first path that includes a first band-pass filter 122.Similarly, the second RF signal can be provided to the LNA circuit 110from the common input node 102 (RF_IN), through a second path thatincludes a second band-pass filter 124.

The LNA circuit 110 can be configured such that the output (RF_OUT) at acommon output node 138 is an amplified RF signal that includes twoseparated frequency bands associated with the first and second RFsignals. As described herein, the LNA circuit 110 can be configured toyield desirable performance features such as low loss, low noise figure,and high isolation between the two input signal paths.

In some embodiments, the LNA circuit 110 can include a plurality ofamplification paths, with each amplification path being divided into acurrent converter portion and an adder portion. In the example of FIG.6, the LNA circuit 110 is shown to include two amplification paths. Thefirst amplification path can include a first input node 132, a firstcurrent converter 142, a common node 136, an adder 146, and an outputnode 138. Similarly, the second amplification path can include a secondinput node 134, a second current converter 144, the common node 136, theadder 146, and the output node 138. More specific examples of the LNAcircuit 110 are described herein in reference to FIGS. 7-9.

In some embodiments, an LNA circuit configured in the foregoing mannercan benefit from reduced noise figure due to, for example, absence of aswitch between a filter and an amplification circuit in a given path.Additionally, such an absence of switches can reduce the size and/orcost associated with the CA architecture. As described herein, such anLNA circuit can be operated in a CA mode with good isolation between theinputs being aggregated. Further, such an LNA circuit can be easilyscalable to accommodate different number of inputs.

FIG. 7 shows an LNA circuit 110 that can be implemented as a morespecific example of the LNA circuit described in reference to FIG. 6.The example of FIG. 7 is a two-input version; however, it will beunderstood that more than two inputs can be implemented.

In FIG. 7, a first current converter 142 is shown to be configured toreceive a first RF signal (RFin1) at a first input node 132, process thefirst RF signal, and output the processed first RF signal to a commonnode 136. Similarly, a second current converter 144 is shown to beconfigured to receive a second RF signal (RFin2) at a second input node134, process the second RF signal, and output the processed second RFsignal to the common node 136. The processed first and second RF signalscan be combined at the common node 136 and be further processed by acommon adder 146 so as to yield an output RF signal (RFout) at an outputnode 138.

In FIG. 7, a combination of the first current converter 142 and thecommon adder 146 can be implemented as a first cascode amplifier.Similarly, a combination of the second current converter 144 and thecommon adder 146 can be implemented as a second cascode amplifier.Accordingly, each of the first and second current converters (142 or144) can provide transconductance amplification functionality for itsrespective RF signal, and the common adder 146 can provide currentbuffer functionality for the combined RF signal.

In FIG. 7, the first current converter 142 is shown to include a bipolarjunction transistor (BJT) Q1 in a common emitter configuration. Thefirst RF signal (RFin1) can be provided from the first input node 132,through a DC block capacitance C1, and to the base of Q1. The outputfrom Q1 can be provided through its collector which is coupled to thecommon node 136. The emitter of Q1 is shown to be coupled to groundthrough an inductance L1. A bias signal for Q1 (Bias1) can be providedto the base of Q1 through a bias switch S1 and a base resistance R1.When Q1 is active, the bias switch S1 can be closed, and a shunt switchS2 can be opened. When Q1 is inactive, the bias switch S1 can be opened,and the shunt switch S2 can be closed. Because the bias switch S1 andthe shunt switch S2 are not directly along the path of the first RFsignal (RFin1), they contribute little or no noise to the first RFsignal.

In FIG. 7, the second current converter 144 is shown to include a BJT Q2in a common emitter configuration. The second RF signal (RFin2) can beprovided from the second input node 134, through a DC block capacitanceC2, and to the base of Q2. The output from Q2 can be provided throughits collector which is coupled to the common node 136. The emitter of Q2is shown to be coupled to ground through an inductance L2. A bias signalfor Q2 (Bias2) can be provided to the base of Q2 through a bias switchS3 and a base resistance R2. When Q2 is active, the bias switch S3 canbe closed, and a shunt switch S4 can be opened. When Q2 is inactive, thebias switch S3 can be opened, and the shunt switch S4 can be closed.Because the bias switch S3 and the shunt switch S4 are not directlyalong the path of the second RF signal (RFin2), they contribute littleor no noise to the second RF signal.

In FIG. 7, the common adder 146 is shown to include a BJT Q3 in a commonbase configuration. The combined RF signal from the common node 136 isshown to be provided to the emitter of Q3, and the output from Q3 isshown to be provided through its collector. The collector is shown to becoupled to the output node 138 so as to yield the output RF signal(RFout). The base of Q3 is shown to be provided with a bias voltageVcas, which can be adjusted depending on the number of active inputs.

FIG. 8 shows an LNA circuit 110 that can be implemented as another morespecific example of the LNA circuit described in reference to FIG. 6.The example of FIG. 8 is a two-input version; however, it will beunderstood that more than two inputs can be implemented. The example ofFIG. 8 is similar to the example of FIG. 7; however, in FIG. 8, theemitters of the BJTs of the first and second current converters share acommon inductance.

More particularly, in FIG. 8, a first current converter 142 is shown tobe configured to receive a first RF signal (RFin1) at a first input node132, process the first RF signal, and output the processed first RFsignal to a common node 136. Similarly, a second current converter 144is shown to be configured to receive a second RF signal (RFin2) at asecond input node 134, process the second RF signal, and output theprocessed second RF signal to the common node 136. The processed firstand second RF signals can be combined at the common node 136 and befurther processed by a common adder 146 so as to yield an output RFsignal (RFout) at an output node 138.

In FIG. 8, a combination of the first current converter 142 and thecommon adder 146 can be implemented as a first cascode amplifier.Similarly, a combination of the second current converter 144 and thecommon adder 146 can be implemented as a second cascode amplifier.Accordingly, each of the first and second current converters (142 or144) can provide transconductance amplification functionality for itsrespective RF signal, and the common adder 146 can provide currentbuffer functionality for the combined RF signal.

In FIG. 8, the first current converter 142 is shown to include a BJT Q1in a common emitter configuration. The first RF signal (RFin1) can beprovided from the first input node 132, through a DC block capacitanceC1, and to the base of Q1. The output from Q1 can be provided throughits collector which is coupled to the common node 136. The emitter of Q1is shown to be coupled to ground through a common inductance L0. A biassignal for Q1 (Bias1) can be provided to the base of Q1 through a biasswitch S1 and a base resistance R1. When Q1 is active, the bias switchS1 can be closed, and a shunt switch S2 can be opened. When Q1 isinactive, the bias switch S1 can be opened, and the shunt switch S2 canbe closed. Because the bias switch S1 and the shunt switch S2 are notdirectly along the path of the first RF signal (RFin1), they contributelittle or no noise to the first RF signal.

In FIG. 8, the second current converter 144 is shown to include a BJT Q2in a common emitter configuration. The second RF signal (RFin2) can beprovided from the second input node 134, through a DC block capacitanceC2, and to the base of Q2. The output from Q2 can be provided throughits collector which is coupled to the common node 136. The emitter of Q2is shown to be coupled to ground through the common inductance L0. Abias signal for Q2 (Bias2) can be provided to the base of Q2 through abias switch S3 and a base resistance R2. When Q2 is active, the biasswitch S3 can be closed, and a shunt switch S4 can be opened. When Q2 isinactive, the bias switch S3 can be opened, and the shunt switch S4 canbe closed. Because the bias switch S3 and the shunt switch S4 are notdirectly along the path of the second RF signal (RFin2), they contributelittle or no noise to the second RF signal.

In FIG. 8, the common adder 146 is shown to include a BJT Q3 in a commonbase configuration. The combined RF signal from the common node 136 isshown to be provided to the emitter of Q3, and the output from Q3 isshown to be provided through its collector. The collector is shown to becoupled to the output node 138 so as to yield the output RF signal(RFout). The base of Q3 is shown to be provided with a bias voltageVcas, which can be adjusted depending on the number of active inputs.

FIG. 9 shows an LNA circuit 110 that can be implemented as another morespecific example of the LNA circuit described in reference to FIG. 6.The example of FIG. 9 is a two-input version; however, it will beunderstood that more than two inputs can be implemented. The example ofFIG. 9 is similar to the example of FIG. 7; however, in FIG. 9, each ofthe first and second current converters is coupled to a separate adder.

In FIG. 9, a first current converter 142 is shown to be configured toreceive a first RF signal (RFin1) at a first input node 132, process thefirst RF signal, and output the processed first RF signal to be furtherprocessed by an adder circuit 146. Similarly, a second current converter144 is shown to be configured to receive a second RF signal (RFin2) at asecond input node 134, process the second RF signal, and output theprocessed second RF signal to be further processed by the adder circuit146. The processed first and second RF signals can be further processedby the adder circuit 146 so as to yield an output RF signal (RFout) atan output node 138.

In FIG. 9, a combination of the first current converter 142 and aportion of the adder circuit 146 can be implemented as a first cascodeamplifier. Similarly, a combination of the second current converter 144and a portion of the adder circuit 146 can be implemented as a secondcascode amplifier. Accordingly, each of the first and second currentconverters (142 or 144) can provide transconductance amplificationfunctionality for its respective RF signal, and their respectiveportions of the adder circuit 146 can provide current bufferfunctionality for the respective RF signal.

In FIG. 9, the first current converter 142 is shown to include a BJT Q1in a common emitter configuration. The first RF signal (RFin1) can beprovided from the first input node 132, through a DC block capacitanceC1, and to the base of Q1. The output from Q1 can be provided throughits collector which is coupled to a corresponding portion of the addercircuit 146. The emitter of Q1 is shown to be coupled to ground throughan inductance L1. A bias signal for Q1 (Bias1) can be provided to thebase of Q1 through a bias switch S1 and a base resistance R1. When Q1 isactive, the bias switch S1 can be closed, and a shunt switch S2 can beopened. When Q1 is inactive, the bias switch S1 can be opened, and theshunt switch S2 can be closed. Because the bias switch S1 and the shuntswitch S2 are not directly along the path of the first RF signal(RFin1), they contribute little or no noise to the first RF signal.

In FIG. 9, the second current converter 144 is shown to include a BJT Q2in a common emitter configuration. The second RF signal (RFin2) can beprovided from the second input node 134, through a DC block capacitanceC2, and to the base of Q2. The output from Q2 can be provided throughits collector which is coupled to a corresponding portion of the addercircuit 146. The emitter of Q2 is shown to be coupled to ground throughan inductance L2. A bias signal for Q2 (Bias2) can be provided to thebase of Q2 through a bias switch S3 and a base resistance R2. When Q2 isactive, the bias switch S3 can be closed, and a shunt switch S4 can beopened. When Q2 is inactive, the bias switch S3 can be opened, and theshunt switch S4 can be closed. Because the bias switch S3 and the shuntswitch S4 are not directly along the path of the second RF signal(RFin2), they contribute little or no noise to the second RF signal.

In FIG. 9, the adder circuit 146 is shown to include a BJT Q3 in acommon base configuration for the BJT Q1 of the first current converter142. The output from the collector of Q1 is shown to be provided to theemitter of Q3, and the output from Q3 is shown to be provided throughits collector. The collector (of Q3) is shown to be coupled to a commonnode 136 where the processed signal from Q3 can combine with a processedsignal from the other cascode amplification path. The base of Q3 isshown to be provided with a first bias voltage Vcas1.

The adder circuit 146 is shown to further include a BJT Q4 in a commonbase configuration for the BJT Q2 of the second current converter 144.The output from the collector of Q2 is shown to be provided to theemitter of Q4, and the output from Q4 is shown to be provided throughits collector. The collector (of Q4) is shown to be coupled to thecommon node 136 where the processed signal from Q4 can combine with aprocessed signal from the other cascode amplification path. The commonnode 136 is shown to be coupled to the output node 138 so as to yieldthe output RF signal (RFout). The base of Q4 is shown to be providedwith a second bias voltage Vcas2.

Other variations at different levels can also be implemented. Forexample, one or more features of the present disclosure can beimplemented in architectures involving LNA and/or other amplificationapplications. In another example, various examples are described in thecontext of cascode configurations; however, it will be understood thatother types of amplification configurations (such as a push-pullconfiguration) can be utilized. In yet another example, various examplesare described in the context of BJTs; however, it will be understoodthat other types of transistors (such as a field-effect transistors(FETs)) can be utilized.

Table 1 lists various performance parameters obtained from simulation ofthe LNA circuit of FIG. 7 configured to support example cellular bandsB30 (2.350 to 2.360 GHz for RX) and B38 (2.570 to 2.620 GHz for RX). Thesimulation was performed at a frequency of approximately 2.355 GHz forthe B30 band, and approximately 2.6 GHz for the B38 band.

TABLE 1 Current Mode Gain (dB) NF (dB) S11 (dB) S22 (dB) (mA) B30(non-CA) 16.8 2.44 −12 −15.2 3.7 B38 (non-CA) 16.5 2.13 −11.7 -23 3.7B30 (CA) 16.1 3.02 −15 −17.2 6.3 B38 (CA) 14.2 2.9 −10.5 −50 6.3

In Table 1, Gain is the overall gain provided by the corresponding RFband path; NF is the noise figure measured at the output of the LNAcircuit (and including diplexer loss and noise from all matchingcomponents); S11 is representative of the input voltage reflectioncoefficient; S22 is representative of the output voltage reflectioncoefficient; and Current is the total current associated with thecorresponding RF band path. One can see that in the CA mode, performanceof the B30 and B38 bands are degraded relatively little.

FIG. 10 shows a process 200 that can be implemented to fabricate adevice having one or more features as described herein. In block 202, acircuit having at least a diplexer functionality can be mounted orprovided on a substrate. In various examples, carrier aggregation (CA)is described in the context of diplexers; however, it will be understoodthat CA can also be implemented with more than two bands (e.g.,utilizing multiplexers). In some embodiments, a diplexer can beimplemented as a device; and such a device can be mounted on thesubstrate.

In block 204, a plurality of current converters for a low-noiseamplifier (LNA) can be formed or provided. In block 206, one or moreadders for the LNA can be formed or provided. In block 208, the outputsof the diplexer circuit can be coupled with the current converters. Inblock 210, the current converters can be coupled with the one or moreadders.

In some embodiments, the device described in FIG. 10 and having one ormore features as described herein can be a module configured for RFapplications. FIG. 11 shows a block diagram of an RF module 300 (e.g., afront-end module) having a packaging substrate 302 such as a laminatesubstrate. Such a module can include one or more LNA circuits; and insome embodiments, such LNA circuit(s) can be implemented on asemiconductor die 306. An LNA circuit implemented on such a die can beconfigured to facilitate CA operation as described herein. Such an LNAcircuit can also provide one or more advantageous features associatedwith improved carrier aggregation (CA) functionalities as describedherein.

The module 300 can further include a plurality of switches implementedon one or more semiconductor die 304. In some embodiments, such switchesare not implemented along RF signal paths between diplexer(s) and theLNA circuit, thereby yielding, for example, improved noise figureperformance.

The module 300 can further include one or more diplexers and/or aplurality of filters (collectively indicated as 310) configured toprocess RF signals. Such diplexers/filters can be implemented assurface-mount devices (SMDs), as part of an integrated circuit (IC), ofsome combination thereof. Such diplexers/filters can include or be basedon, for example, SAW filters, and can be configured as high Q devices.

In some implementations, an architecture, device and/or circuit havingone or more features described herein can be included in an RF devicesuch as a wireless device. Such an architecture, device and/or circuitcan be implemented directly in the wireless device, in one or moremodular forms as described herein, or in some combination thereof. Insome embodiments, such a wireless device can include, for example, acellular phone, a smart-phone, a hand-held wireless device with orwithout phone functionality, a wireless tablet, a wireless router, awireless access point, a wireless base station, etc. Although describedin the context of wireless devices, it will be understood that one ormore features of the present disclosure can also be implemented in otherRF systems such as base stations.

FIG. 12 schematically depicts an example wireless device 400 having oneor more advantageous features described herein. In some embodiments,such advantageous features can be implemented in a front-end (FE) module300 as described herein. In some embodiments, such an FEM can includemore or less components than as indicated by the dashed box.

Power amplifiers (PAs) in a PA module 412 can receive their respectiveRF signals from a transceiver 410 that can be configured and operated togenerate RF signals to be amplified and transmitted, and to processreceived signals. The transceiver 410 is shown to interact with abaseband sub-system 408 that is configured to provide conversion betweendata and/or voice signals suitable for a user and RF signals suitablefor the transceiver 410. The transceiver 410 is also shown to beconnected to a power management component 406 that is configured tomanage power for the operation of the wireless device 400. Such powermanagement can also control operations of the baseband sub-system 408and other components of the wireless device 400.

The baseband sub-system 408 is shown to be connected to a user interface402 to facilitate various input and output of voice and/or data providedto and received from the user. The baseband sub-system 408 can also beconnected to a memory 404 that is configured to store data and/orinstructions to facilitate the operation of the wireless device, and/orto provide storage of information for the user.

In the example wireless device 400, the front-end module 300 can includeone or more carrier aggregation-capable signal paths configured toprovide one or more functionalities as described herein. Such signalpaths can be in communication with an antenna switch module (ASM) 414through their respective diplexer(s). In some embodiments, at least someof the signals received through an antenna 420 can be routed from theASM 414 to one or more low-noise amplifiers (LNAs) 418 in manners asdescribed herein. Amplified signals from the LNAs 418 are shown to berouted to the transceiver 410. In some embodiments, at least some of theLNAs 418 can include an LNA circuit 110 having one or more features asdescribed herein.

FIG. 13 schematically depicts an example wireless device 500 having oneor more advantageous features described herein. In some embodiments,such advantageous features can be implemented in a front-end (FE) module300 as described herein. In some embodiments, such an FEM can includemore or less components than as indicated by the dashed box.

PAs in a PA module 512 can receive their respective RF signals from atransceiver 510 that can be configured and operated to generate RFsignals to be amplified and transmitted, and to process receivedsignals. The transceiver 510 is shown to interact with a basebandsub-system 508 that is configured to provide conversion between dataand/or voice signals suitable for a user and RF signals suitable for thetransceiver 510. The transceiver 510 is also shown to be connected to apower management component 506 that is configured to manage power forthe operation of the wireless device 500. Such power management can alsocontrol operations of the baseband sub-system 508 and other componentsof the wireless device 500.

The baseband sub-system 508 is shown to be connected to a user interface502 to facilitate various input and output of voice and/or data providedto and received from the user. The baseband sub-system 508 can also beconnected to a memory 504 that is configured to store data and/orinstructions to facilitate the operation of the wireless device, and/orto provide storage of information for the user.

In the example wireless device 500, the front-end module 300 can includeone or more carrier aggregation-capable signal paths configured toprovide one or more functionalities as described herein. Such signalpaths can be in communication with an antenna switch module (ASM) 524through their respective diplexer(s). In some embodiments, at least someof the signals received through a diversity antenna 530 can be routedfrom the ASM 524 to one or more low-noise amplifiers (LNAs) 418 inmanners as described herein. Amplified signals from the LNAs 418 areshown to be routed to the transceiver 510.

A number of other wireless device configurations can utilize one or morefeatures described herein. For example, a wireless device does not needto be a multi-band device. In another example, a wireless device caninclude additional antennas such as diversity antenna, and additionalconnectivity features such as Wi-Fi, Bluetooth, and GPS.

Examples Related to Diversity Receive (DRx) Implementation:

Using one or more main antennas and one or more diversity antennas in awireless device can improve quality of signal reception. For example, adiversity antenna can provide additional sampling of RF signals in thevicinity of the wireless device. Additionally, a wireless device'stransceiver can be configured to process the signals received by themain and diversity antennas to obtain a receive signal of higher energyand/or improved fidelity, when compared to a configuration using onlythe main antenna.

To reduce the correlation between signals received by the main anddiversity antennas and/or to enhance antenna isolation, the main anddiversity antennas can be separated by a relatively large physicaldistance in the wireless device. For example, the diversity antenna canbe positioned near the top of the wireless device and the main antennacan be positioned near the bottom of the wireless device, or vice-versa.

The wireless device can transmit or receive signals using the mainantenna by routing corresponding signals from or to the transceiverthrough an antenna switch module. To meet or exceed designspecifications, the transceiver, the antenna switch module, and/or themain antenna can be in relatively close physical proximity to oneanother in the wireless device. Configuring the wireless device in thismanner can provide relatively small signal loss, low noise, and/or highisolation.

In the foregoing example, the main antenna being physically close to theantenna switch module can result in the diversity antenna beingpositioned relatively far from the antenna switch module. In such aconfiguration, a relatively long signal path between the diversityantenna and the antenna switch module can result in significant lossand/or addition of loss associated with the signal received through thediversity antenna. Accordingly, processing of the signal receivedthrough the diversity antenna, including implementation of one or morefeatures as described herein, in the close proximity to the diversityantenna can be advantageous.

FIG. 14 shows that in some embodiments, one or more features of thepresent disclosure can be implemented in a diversity receive (DRx)module 300. Such a module can include a packaging substrate 302 (e.g., alaminate substrate) configured to receive a plurality of components, aswell to provide or facilitate electrical connections associated withsuch components.

In the example of FIG. 14, the DRx module 300 can be configured toreceive an RF signal from a diversity antenna (not shown in FIG. 14) atan input 320 and route such an RF signal to a low-noise amplifier (LNA)332. It will be understood that such routing of the RF signal caninvolve carrier-aggregation (CA) and/or non-CA configurations. It willalso be understood that although one LNA (e.g., a broadband LNA) isshown, there may be more than one LNAs in the DRx module 300. Dependingon the type of LNA and the mode of operation (e.g., CA or non-CA), anoutput 334 of the LNA 332 can include one or more frequency componentsassociated with one or more frequency bands.

In some embodiments, some or all of the foregoing routing of the RFsignal between the input 320 and the LNA 332 can be facilitated by anassembly of one or more switches 322 between the input 320 and anassembly of diplexer(s) and/or filter(s) (collectively indicated as324), and an assembly of one or more switches 330 between thediplexer/filter assembly 324 and the LNA 332. In some embodiments, theswitch assemblies 322, 330 can be implemented on, for example, one ormore silicon-on-insulator (SOI) die. In some embodiments, some or all ofthe foregoing routing of the RF signal between the input 320 and the LNA332 can be achieved without some or all of the switches associated withthe switch-assemblies 322, 330.

In the example of FIG. 14, the diplexer/filter assembly 324 is depictedas including two example diplexers 326 and two individual filters 328.It will be understood that the DRx module 300 can have more or lessnumbers of diplexers, and more or less numbers of individual filters.Such diplexer(s)/filter(s) can be implemented as, for example,surface-mount devices (SMDs), as part of an integrated circuit (IC), ofsome combination thereof. Such diplexers/filters can include or be basedon, for example, SAW filters, and can be configured as high Q devices.

In some embodiments, the DRx module 300 can include a control componentsuch as a MIPI RFFE interface 340 configured to provide and/orfacilitate control functionalities associated with some or all of theswitch assemblies 322, 330 and the LNA 332. Such a control interface canbe configured to operate with one or more I/O signals 342.

FIG. 15 shows that in some embodiments, a DRx module 300 having one ormore features as described herein (e.g., DRx module 300 of FIG. 14) canbe included in an RF device such as a wireless device 500. In such awireless device, components such as user interface 502, memory 504,power management 506, baseband sub-system 508, transceiver 510, poweramplifier (PA) 512, antenna switch module (ASM) 514, and antenna 520 canbe generally similar to the examples of FIGS. 12 and 13.

In some embodiments, the DRx module 300 can be implemented between oneor more diversity antennas and the ASM 514. Such a configuration canallow an RF signal received through the diversity antenna 530 to beprocessed (in some embodiments, including amplification by an LNA) withlittle or no loss of and/or little or no addition of noise to the RFsignal from the diversity antenna 530. Such processed signal from theDRx module 300 can then be routed to the ASM through one or more signalpaths 532 which can be relatively lossy.

In the example of FIG. 15, the RF signal from the DRx module 300 can berouted through the ASM 514 to the transceiver 510 through one or morereceive (Rx) paths. Some or all of such Rx paths can include theirrespective LNA(s). In some embodiments, the RF signal from the DRxmodule 300 may or may not be further amplified with such LNA(s).

One or more features of the present disclosure can be implemented withvarious cellular frequency bands as described herein. Examples of suchbands are listed in Table 2. It will be understood that at least some ofthe bands can be divided into sub-bands. It will also be understood thatone or more features of the present disclosure can be implemented withfrequency ranges that do not have designations such as the examples ofTable 2.

TABLE 2 Band Mode Tx Frequency Range (MHz) Rx Frequency Range (MHz) B1FDD 1,920-1,980 2,110-2,170 B2 FDD 1,850-1,910 1,930-1,990 B3 FDD1,710-1,785 1,805-1,880 B4 FDD 1,710-1,755 2,110-2,155 B5 FDD 824-849869-894 B6 FDD 830-840 875-885 B7 FDD 2,500-2,570 2,620-2,690 B8 FDD880-915 925-960 B9 FDD 1,749.9-1,784.9 1,844.9-1,879.9 B10 FDD1,710-1,770 2,110-2,170 B11 FDD 1,427.9-1,447.9 1,475.9-1,495.9 B12 FDD699-716 729-746 B13 FDD 777-787 746-756 B14 FDD 788-798 758-768 B15 FDD1,900-1,920 2,600-2,620 B16 FDD 2,010-2,025 2,585-2,600 B17 FDD 704-716734-746 B18 FDD 815-830 860-875 B19 FDD 830-845 875-890 B20 FDD 832-862791-821 B21 FDD 1,447.9-1,462.9 1,495.9-1,510.9 B22 FDD 3,410-3,4903,510-3,590 B23 FDD 2,000-2,020 2,180-2,200 B24 FDD 1,626.5-1,660.51,525-1,559 B25 FDD 1,850-1,915 1,930-1,995 B26 FDD 814-849 859-894 B27FDD 807-824 852-869 B28 FDD 703-748 758-803 B29 FDD N/A 716-728 B30 FDD2,305-2,315 2,350-2,360 B31 FDD 452.5-457.5 462.5-467.5 B33 TDD1,900-1,920 1,900-1,920 B34 TDD 2,010-2,025 2,010-2,025 B35 TDD1,850-1,910 1,850-1,910 B36 TDD 1,930-1,990 1,930-1,990 B37 TDD1,910-1,930 1,910-1,930 B38 TDD 2,570-2,620 2,570-2,620 B39 TDD1,880-1,920 1,880-1,920 B40 TDD 2,300-2,400 2,300-2,400 B41 TDD2,496-2,690 2,496-2,690 B42 TDD 3,400-3,600 3,400-3,600 B43 TDD3,600-3,800 3,600-3,800 B44 TDD 703-803 703-803

For the purpose of description, it will be understood that“multiplexer,” “multiplexing” and the like can include “diplexer,”“diplexing” and the like.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense, as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to.” The word “coupled”, as generally usedherein, refers to two or more elements that may be either directlyconnected, or connected by way of one or more intermediate elements.Additionally, the words “herein,” “above,” “below,” and words of similarimport, when used in this application, shall refer to this applicationas a whole and not to any particular portions of this application. Wherethe context permits, words in the above Detailed Description using thesingular or plural number may also include the plural or singular numberrespectively. The word “or” in reference to a list of two or more items,that word covers all of the following interpretations of the word: anyof the items in the list, all of the items in the list, and anycombination of the items in the list.

The above detailed description of embodiments of the invention is notintended to be exhaustive or to limit the invention to the precise formdisclosed above. While specific embodiments of, and examples for, theinvention are described above for illustrative purposes, variousequivalent modifications are possible within the scope of the invention,as those skilled in the relevant art will recognize. For example, whileprocesses or blocks are presented in a given order, alternativeembodiments may perform routines having steps, or employ systems havingblocks, in a different order, and some processes or blocks may bedeleted, moved, added, subdivided, combined, and/or modified. Each ofthese processes or blocks may be implemented in a variety of differentways. Also, while processes or blocks are at times shown as beingperformed in series, these processes or blocks may instead be performedin parallel, or may be performed at different times.

The teachings of the invention provided herein can be applied to othersystems, not necessarily the system described above. The elements andacts of the various embodiments described above can be combined toprovide further embodiments.

While some embodiments of the inventions have been described, theseembodiments have been presented by way of example only, and are notintended to limit the scope of the disclosure. Indeed, the novel methodsand systems described herein may be embodied in a variety of otherforms; furthermore, various omissions, substitutions and changes in theform of the methods and systems described herein may be made withoutdeparting from the spirit of the disclosure. The accompanying claims andtheir equivalents are intended to cover such forms or modifications aswould fall within the scope and spirit of the disclosure.

What is claimed is:
 1. A carrier aggregation (CA) circuit comprising afirst filter configured to allow operation in a first frequency band; asecond filter configured to allow operation in a second frequency band;a first signal path implemented between the first filter and an outputnode, the first signal path including a plurality of amplificationstages configured to amplify a first radio-frequency (RF) signal, thefirst signal path substantially free of switches; and a second signalpath implemented between the second filter and the output node, thesecond signal path including a plurality of amplification stagesconfigured to amplify a second RF signal, the second signal pathsubstantially free of switches.
 2. The CA circuit of claim 1 wherein thefirst signal path and the second signal path are parts of a low-noiseamplifier (LNA).
 3. The CA circuit of claim 2 wherein the first signalpath and the second signal path being substantially free of switchesallows the CA circuit to operate with a reduced noise figure.
 4. The CAcircuit of claim 2 wherein the plurality of amplification stages of eachof the first signal path and the second signal path includes a firststage configured to convert the respective RF signal into a current, anda second stage configured to add the current.
 5. The CA circuit of claim4 wherein the first stage of each of the first signal path and thesecond signal path includes a first bipolar junction transistor (BJT)configured to receive the respective RF signal through its base andyield an output through its collector.
 6. The CA circuit of claim 5further comprising a bias circuit coupled to the first BJT, the biascircuit including a switchable bias supply path between a bias node andthe base, the switchable bias supply path configured to be capable ofbeing turned on or off to activate or deactivate the respective firstBJT.
 7. The CA circuit of claim 6 wherein the bias circuit furtherincludes a switchable shunt path configured to provide a shunt path whenthe respective first BJT is deactivated.
 8. The CA circuit of claim 5wherein the first BJT of each of the first signal path and the secondsignal path includes an emitter coupled to ground through an inductance.9. The CA circuit of claim 5 wherein the second stages of the firstsignal path and the second signal path are provided by a shared secondBJT configured to receive the RF signals from the first BJTs through itsemitter and yield an output through its collector.
 10. The CA circuit ofclaim 9 wherein the shared second BJT is configured to receive a cascodebias voltage Vcas through its base.
 11. The CA circuit of claim 5wherein the second stage of each of the first signal path and the secondsignal path includes a separate second BJT configured to receive the RFsignal from the respective first BJT through its emitter and yield anoutput through its collector.
 12. The CA circuit of claim 11 whereineach separate second BJT is configured to receive its respective cascodebias voltage Vcas through its base.
 13. The CA circuit of claim 4wherein each of the first signal path and the second signal path iscapable of being in an active state or an inactive state to allow the CAcircuit to operate in a CA mode or a non-CA mode without separateswitches along the first signal path and the second signal path.
 14. TheCA circuit of claim 13 wherein the active state or the inactive statefor each of the first signal path and the second signal path is achievedby activating or deactivating the respective first stage.
 15. Aradio-frequency (RF) module comprising: a packaging substrate configuredto receive a plurality of components; and a carrier aggregation (CA)circuit implemented on the packaging substrate, the CA circuit includinga first filter configured to allow operation in a first frequency bandand a second filter configured to allow operation in a second frequencyband, the CA circuit further including a first signal path implementedbetween the first filter and an output node, the first signal pathincluding a plurality of amplification stages configured to amplify afirst radio-frequency (RF) signal, the first signal path substantiallyfree of switches, the CA circuit further including a second signal pathimplemented between the second filter and the output node, the secondsignal path including a plurality of amplification stages configured toamplify a second RF signal, the second signal path substantially free ofswitches.
 16. The RF module of claim 15 wherein each of the first filterand the second filter includes a surface acoustic wave (SAW) filter. 17.The RF module of claim 16 wherein the RF module is a diversity receive(DRx) module.
 18. A wireless device comprising: a receiver configured toprocess radio-frequency (RF) signals; an RF module in communication withthe receiver, the RF module including a carrier aggregation (CA)circuit, the CA circuit including a first filter configured to allowoperation in a first frequency band and a second filter configured toallow operation in a second frequency band, the CA circuit furtherincluding a first signal path implemented between the first filter andan output node, the first signal path including a plurality ofamplification stages configured to amplify a first radio-frequency (RF)signal, the first signal path substantially free of switches, the CAcircuit further including a second signal path implemented between thesecond filter and the output node, the second signal path including aplurality of amplification stages configured to amplify a second RFsignal, the second signal path substantially free of switches; and anantenna in communication with the RF module, the antenna configured toreceive the RF signals.
 19. The wireless device of claim 18 wherein theantenna includes a diversity antenna, and the RF module includes adiversity receive (DRx) module).
 20. The wireless device of claim 19further comprising an antenna switch module (ASM) configured to routethe RF signals from the diversity antenna to the receiver, such that theDRx module is implemented between the diversity antenna and the ASM.